Vascular disease affects a large proportion of individuals each year. One indication of the existence of this disease is the development of a blood clot in the vascular system, which if left untreated may result in deep venous thrombosis, embolisms, or ischemia. These clots, which may either partially or fully occlude a vessel, are usually comprised of an aggregated mixture of thrombus and fibrin.
Various known techniques for the removal of blood clots include both chemical and mechanical treatment. Chemical treatment typically involves the injection of lysing agents into the vessel near the blood clot to chemically attack, dissolve, and disperse the occlusion. Such lysing or thrombolytic agents include plasmin, streptokinase, alteplase, tenecteplase, and reteplase. In this technique, the lysing agent is brought into the proximate vicinity of the blood clot via injection through a cannula or other lumen.
The mechanical treatment of a blood clot typically involves the use of catheters having a rotary cutting head or other form of a rotor/stator homogenizing head. Examples of such rotary devices include rotating burr devices, rotating a helical coil wire within a catheter, and recanalization catheters. Other mechanical devices utilize a sharp point to methodically pummel the occlusion in order to form a hole through it. In each of these cases, although the occlusion is reduced in size or a passageway is created, the residual thrombus/fibrin material resulting from the treatment remains within the vessel.
The removal of residual material formed during the fragmentation of a blood clot is medically desirable. It is further necessary to insure that this residual material does not migrate away from the site of the treatment to other parts of the vessel. Such migration could lead to serious complications, such as embolism, stroke, or a heart attack. The use of a vena cava filter has been employed to catch residual fragments that have migrated from the site of a blood clot. In addition, some mechanical devices have utilized the concept of aspiration to establish or maintain a flow rate through a catheter for the removal of residual thrombus/fibrin material during treatment.
Therefore, there is a need to create a medical device in which the element of the device used to clear an occlusion is shielded from contact with the vessel wall, and in which any resulting residual material may be effectively removed from the vessel.